Radiation levels at the Martian surface appear to be roughly similar to those experienced by astronauts in low-Earth orbit, NASA's Mars rover Curiosity has found.

The rover's initial radiation measurements — the first ever taken on the surface of another planet — may buoy the hopes of human explorers who may one day put boots on Mars, for they add more support to the notion that astronauts can indeed function on the Red Planet for limited stretches of time.

"Absolutely, astronauts can live in this environment," Don Hassler, of the Southwest Research Institute in Boulder, Colo., told reporters during a news conference Thursday.

Hassler is principal investigator of Curiosity's Radiation Assessment Detector instrument, or RAD. RAD aims to characterize the Martian radiation environment, both to help scientists assess the planet's past and current potential to host life and to aid future manned exploration of the Red Planet. [ Video: Curiosity Takes First Cosmic Ray Sample on Surface ]

Since Curiosity landed on Mars in August, RAD has measured radiation levels broadly comparable to those experienced by crew members of the International Space Station, Hassler said. Radiation at the Martian surface is about half as high as the levels Curiosity experienced during its nine-month cruise through deep space, he added.

The findings demonstrate that Mars' atmosphere, though just 1 percent as thick as that of Earth, does provide a significant amount of shielding from dangerous, fast-moving cosmic particles. (Mars lacks a magnetic field, which gives our planet another layer of protection.)

The $2.5 billion Curiosity rover is getting a bead on the nature of this shielding. RAD has observed that radiation levels rise and fall by 3 to 5 percent over the course of each day, coincident with the daily thickening and thinning of the Martian atmosphere, researchers said.

Hassler stressed that RAD's findings are preliminary, as Curiosity is just three months into a planned two-year prime mission. He and his team have not yet put hard numbers on the Martian radiation levels, though they plan to do so soon.

"We're working on that, and we're hoping to release that at the AGU meeting in December," Hassler said, referring to the American Geophysical Union's huge conference in San Francisco, which runs from Dec. 3-7. "Basically, there's calibrations and characterizations that we're finalizing to get those numbers precise."

The real issue for human exploration, he said, is determining how much of a radiation dose any future astronauts would accumulate throughout an entire Mars mission — during the cruise to the Red Planet, the time on the surface and the journey home.

"Over time, we're going to get those numbers," Hassler said.

One key to understanding the big picture will be documenting the effects of big solar storms, which can blast huge clouds of charged particles into space. Curiosity flew through one such cloud on its way to Mars but has yet to experience one on the surface, Hassler said.

NASA / JPL-Caltech / SwRI

This graphic shows the daily variations in Martian radiation and atmospheric pressure as measured by NASA's Curiosity rover.

RAD is just one of Curiosity's 10 different science instruments, which it's using to determine if the Red Planet could ever have supported microbial life. During today's press conference, researchers also detailed some initial findings about the Martian atmosphere, including interesting wind patterns and details about daily changes in atmospheric density.

"If we can find out more about the weather and climate on present-day Mars, then that really helps us to improve our understanding of Mars' atmospheric processes," said Claire Newman of Ashima Research in Pasadena, Calif., a collaborator for Curiosity's Rover Environmental Monitoring Station instrument. "That gives us much more confidence when we try to predict things like what Mars may have looked like in the past."

Caring for Curiosity

NASA's Curiosity rover is as big as a compact car and weighs a ton ... and it's on Mars. Here's where the journey began. A white-room team works on the six-wheeled spacecraft on Aug. 13, 2011, at the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida.
(NASA via Getty Images)
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Curious about Curiosity

Jasper Goldberg and Andreas Bastian, both 22, watch live NASA coverage of Curiosity's descent to Mars on the giant video screen in New York's Times Square.
(Andrew Burton / Reuters)
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Watching and waiting

Steve Collins waits for word at the Jet Propulsion Laboratory's mission control room during the "seven minutes of terror" as Curiosity approaches the surface of Mars on Aug. 5. Collins was working at JPL in 1993 when NASA's Mars Observer probe was lost just before its scheduled arrival at the Red Planet.
(Fred Prouser / Reuters)
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Touchdown!

The Mars Science Laboratory team in the Mission Support Area at NASA's Jet Propulsion Laboratory reacts after learning that the Curiosity rover has landed safely on Mars. The happy news came at 10:31 p.m. PT Aug. 5 (1:31 a.m. ET Aug. 6).
(Bill Ingalls / NASA via Reuters)
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From Mars to Times Square

Great catch!

As it flew high above, NASA's Mars Reconnaissance Orbiter captured this picture of the Curiosity rover and its parachute descending to the Martian surface on Aug. 5. The inset image has been processed to bring out additional detail in the view of the rover and the chute.
(NASA / JPL-Caltech via AP)
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Flying saucer

A color image shows the Mars Science Laboratory's heat shield, as seen by a camera on the Curiosity rover during the spacecraft's descent on Aug. 5. The picture was obtained by the Mars Descent Imager instrument, also known as MARDI, and shows the 15-foot (4.5-meter) diameter heat shield when it was flying away 50 feet (16 meters) below the spacecraft. This image shows the inside surface of the heat shield, with its protective multilayered insulation.
(NASA / JPL-Caltech / MSSS)
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The mountain ahead

One of the first views from NASA's Curiosity rover, which landed on Mars on Aug. 5, shows the rover's shadow in the foreground and a 3-mile-high mountain known as Aeolis Mons or Mount Sharp in the distance. That mountain is the rover's eventual destination. The picture was taken through a "fisheye" wide-angle lens by one of the rover's hazard avoidance cameras.
(NASA / JPL-Caltech via AFP - Getty)
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Miles and miles on Mars

This image, released on Aug. 9, shows part of the deck of NASA's Curiosity rover as seen by one of the rover's navigation cameras. The rover's pointy low-gain antenna and its paddle-shaped high-gain antenna are among the pieces of hardware visible in the foreground. The rim of Gale Crater can be seen at the horizon.
(NASA / JPL-Caltech via AFP - Getty)
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Curiosity's crime scene

The four main pieces of hardware that arrived on Mars with NASA's Curiosity rover are pinpointed in this image from NASA's Mars Reconnaissance Orbiter, taken 24 hours after landing. The heat shield was the first piece to hit the ground, followed by the back shell attached to the parachute. The rover itself was lowered to the ground on cables by its rocket-powered sky crane. The cables were cut, and then the sky crane flew away to its own crash landing.
(NASA / JPL-Caltech via Getty Images)
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What a blast!

This is a portion of the first 360-degree black-and-white panoramic view acquired by the navigation cameras aboard NASA's Curiosity rover. Two disturbed areas are visible in the foreground, where the rocket thrusters on Curiosity's sky crane blasted away the surface gravel to reveal bedrock below. The high country of Gale Crater's rim can be seen in the distance.
(NASA / JPL-Caltech via AFP - Getty)
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First color picture

An image from the Curiosity rover's Mars Hand Lens Imager, or MAHLI, provides the first color view of the north wall and rim of Gale Crater. The picture was taken by the MAHLI camera at the end of Curiosity's stowed robotic arm. The view appears fuzzy because of the dust that has settled on the camera's removable cover.
(NASA / JPL-Caltech / MSSS via AP)
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Mars in living color

A color image from NASA's Curiosity Rover shows the pebble-covered surface of Mars. This is a portion of the first color 360-degree panorama from NASA's Curiosity rover, made up of thumbnails, which are small copies of higher-resolution images. The mission's destination, a mountain at the center of Gale Crater called Aeolis Mons or Mount Sharp, can be seen in the distance rising up toward the left. Blast marks from the rover's descent stage are in the foreground.
(NASA / JPL-Caltech / MSSS / Getty Images)
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Pew-pew

This composite image, with magnified insets, shows the results of the first laser test by the ChemCam instrument aboard NASA's Curiosity rover on Mars. The composite incorporates a Navcam image taken prior to the test, with insets taken by the camera in ChemCam. The circular insert highlights the rock before the laser test. The square inset is further magnified and processed to show the effect of the laser blasts on Aug. 19.
(LANL / MSSS / JPL-Caltech / NASA via Reuters)
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Future mapped out

NASA's Curiosity rover landed inside Gale Crater at the green dot, within the Yellowknife quadrangle, on Aug. 5. The team has decided to send it first to the region marked by a blue dot, that is nicknamed Glenelg. That area marks the intersection of three kinds of terrain. Then the rover will aim for the blue spot marked "Base of Mt. Sharp," where a natural break in Martian sand dunes will provide an opening for Curiosity to begin scaling the lower reaches of Mount Sharp.
(Univ. of Ariz. / JPL-Caltech / NASA via Reuters)
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First steps

Curiosity's navigation camera system looks back at the wheel tracks from the rover's first test drive on Aug. 22. The $2.5 billion rover made its first moves a little more than two weeks after its arrival on Mars.
(JPL-Caltech / NASA via AFP - Getty Images)
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Mount Sharp

Mount Sharp is seen in the distance in an image taken Aug. 23 by the 34-millimeter Mast Camera on Curiosity. The gravelly area around Curiosity's landing site is visible in the foreground. Farther away, about a third of the way up from the bottom of the image, the terrain falls off into a depression (a swale). Beyond the swale, in the middle of the image, is the boulder-strewn, red-brown rim of a moderately-sized impact crater. Father off in the distance, there are dark dunes and then the layered rock at the base of Mount Sharp. Some haze obscures the view, but the top ridge, depicted in this image, is 10 miles (16.2 kilometers) away. Scientists enhanced the color to show the Martian scene under the lighting conditions we have on Earth.
(NASA via AFP - Getty Images)
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Hip-hop on Mars

Will.i.am of the Black Eyed Peas sings at NASA's Jet Propulsion Laboratory on Aug. 28. Will.i.am's "Reach for the Stars" officially became the first song broadcast from Mars, thanks to a signal beamed from Curiosity.
(Nick Ut / AP)
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Mmm, Marsberries!

Small spherical objects fill the field in this Martian mosaic combining four images from the Microscopic Imager on NASA's Opportunity rover. The Sept. 6 view covers an area about 2.4 inches (6 centimeters) across, at an outcrop called Kirkwood in the Cape York segment of the western rim of Mars' Endeavour Crater. Shortly after its landing in 2004, Opportunity spotted similar spherules that were nicknamed "blueberries," but these berries are not as rich in iron, posing a scientific puzzle.
(NASA/JPL-Caltech/Cornell Univ./ USGS/Modesto Junior College via EPA)
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'Do I look fat?' Curiosity checks its belly

A mosaic of photos taken on Sept. 9 by the Mars Hand Lens Imager on NASA's Curiosity rover shows the underside of the rover and its six wheels, with Martian terrain stretching back to the horizon. The four circular features on the front edge of the rover are the lenses for the left and right sets of Curiosity's hazard avoidance cameras, or Hazcams. Because of the different perspectives used for different images, some of the borders of the photos don't line up precisely.
(NASA via AFP - Getty Images)
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A Martian rock called Jake

NASA's Curiosity rover stopped about 8 feet (2.5 meters) in front of this Red Planet rock on Sept. 19, the mission's 43rd Martian day, or sol. The pyramid-shaped chunk was the first rock that the Curiosity rover touched for science's sake. It was named "Jake Matijevic" in honor of a top engineer who worked on every one of NASA's rover missions — but passed away just days after Curiosity's landing. Jake the rock, which measures about 10 inches (25 centimeters) tall, provided a good reference point for the rover's sophisticated instruments.
(NASA via Getty Images)
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Rover's footprint

NASA's Curiosity rover cut a wheel scuff mark into a wind-formed ripple at the "Rocknest" site on Mars to give researchers a better opportunity to examine the particle-size distribution of the material forming the ripple. The rover's right navigation camera took this image of the scuff mark on the mission's 57th Martian day, or sol (Oct. 3), the same sol that a wheel created the mark. For scale, the width of the wheel track is about 16 inches (40 centimeters).
(Handout / Reuters)
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Rover's self-portrait

The Curiosity rover used the Mars Hand Lens Imager (MAHLI) to capture the set of thumbnail images stitched together to create this full-color self-portrait in this Oct. 31, 2012 image from NASA.
(NASA via Reuters)
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Life on Mars?

The first sample of powdered rock extracted by the drill of Curiosity is seen on Feb. 20, 2013. Powder drilled out of a rock on Mars contains the best evidence yet that the Red Planet could have supported living microbes billions of years ago, the team behind NASA's Curiosity rover said March 12, 2013.

The big picture

This picture isn't from the Curiosity rover - it's a 2003 image from the Hubble Space Telescope, showing the full disk of Mars. The big picture hints at how much we'll be learning about the Red Planet during Curiosity's two-year, $2.5 billion mission. And that's just the beginning: Scientists hope the nuclear-powered rover will last years or even decades longer.
(NASA via AP)
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Editor's note:
This image contains graphic content that some viewers may find disturbing.